84 lines
3.6 KiB
Plaintext
84 lines
3.6 KiB
Plaintext
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Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for
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8-/16-bit I/O expander with serial interface (I2C/SPI)
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Required properties:
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- compatible : Should be
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- "mcp,mcp23s08" (DEPRECATED) for 8 GPIO SPI version
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- "mcp,mcp23s17" (DEPRECATED) for 16 GPIO SPI version
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- "mcp,mcp23008" (DEPRECATED) for 8 GPIO I2C version or
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- "mcp,mcp23017" (DEPRECATED) for 16 GPIO I2C version of the chip
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- "microchip,mcp23s08" for 8 GPIO SPI version
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- "microchip,mcp23s17" for 16 GPIO SPI version
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- "microchip,mcp23008" for 8 GPIO I2C version or
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- "microchip,mcp23017" for 16 GPIO I2C version of the chip
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NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
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removed.
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- #gpio-cells : Should be two.
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- first cell is the pin number
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- second cell is used to specify flags. Flags are currently unused.
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- gpio-controller : Marks the device node as a GPIO controller.
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- reg : For an address on its bus. I2C uses this a the I2C address of the chip.
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SPI uses this to specify the chipselect line which the chip is
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connected to. The driver and the SPI variant of the chip support
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multiple chips on the same chipselect. Have a look at
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microchip,spi-present-mask below.
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Required device specific properties (only for SPI chips):
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- mcp,spi-present-mask (DEPRECATED)
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- microchip,spi-present-mask : This is a present flag, that makes only sense for SPI
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chips - as the name suggests. Multiple SPI chips can share the same
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SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a
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chip connected with the corresponding spi address set. For example if
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you have a chip with address 3 connected, you have to set bit3 to 1,
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which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not
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possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at
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least one bit to 1 for SPI chips.
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NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
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removed.
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- spi-max-frequency = The maximum frequency this chip is able to handle
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Optional properties:
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- #interrupt-cells : Should be two.
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- first cell is the pin number
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- second cell is used to specify flags.
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- interrupt-controller: Marks the device node as a interrupt controller.
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NOTE: The interrupt functionality is only supported for i2c versions of the
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chips. The spi chips can also do the interrupts, but this is not supported by
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the linux driver yet.
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Optional device specific properties:
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- microchip,irq-mirror: Sets the mirror flag in the IOCON register. Devices
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with two interrupt outputs (these are the devices ending with 17 and
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those that have 16 IOs) have two IO banks: IO 0-7 form bank 1 and
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IO 8-15 are bank 2. These chips have two different interrupt outputs:
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One for bank 1 and another for bank 2. If irq-mirror is set, both
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interrupts are generated regardless of the bank that an input change
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occurred on. If it is not set, the interrupt are only generated for the
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bank they belong to.
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On devices with only one interrupt output this property is useless.
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Example I2C (with interrupt):
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gpiom1: gpio@20 {
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compatible = "microchip,mcp23017";
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gpio-controller;
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#gpio-cells = <2>;
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reg = <0x20>;
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interrupt-parent = <&gpio1>;
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interrupts = <17 IRQ_TYPE_LEVEL_LOW>;
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interrupt-controller;
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#interrupt-cells=<2>;
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microchip,irq-mirror;
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};
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Example SPI:
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gpiom1: gpio@0 {
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compatible = "microchip,mcp23s17";
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gpio-controller;
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#gpio-cells = <2>;
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spi-present-mask = <0x01>;
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reg = <0>;
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spi-max-frequency = <1000000>;
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};
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